Add stats for rendered pixels (sqrt(w*h)) per second:

webrtc/video/receive_statistics_proxy.h

Index: webrtc/video/receive_statistics_proxy.h
diff --git a/webrtc/video/receive_statistics_proxy.h b/webrtc/video/receive_statistics_proxy.h
index 4f2550ad7e2496b0c87d9037946fd4748c3fe635..f5957ff53ed3cacab2916b92f385c6be20bca3a8 100644
--- a/webrtc/video/receive_statistics_proxy.h
+++ b/webrtc/video/receive_statistics_proxy.h
@@ -91,6 +91,7 @@ class ReceiveStatisticsProxy : public VCMReceiveStatisticsCallback,
   RateStatistics decode_fps_estimator_ GUARDED_BY(crit_);
   RateStatistics renders_fps_estimator_ GUARDED_BY(crit_);
   rtc::RateTracker render_fps_tracker_ GUARDED_BY(crit_);
+  rtc::RateTracker render_pixel_tracker_ GUARDED_BY(crit_);
   SampleCounter render_width_counter_ GUARDED_BY(crit_);
   SampleCounter render_height_counter_ GUARDED_BY(crit_);
   SampleCounter decode_time_counter_ GUARDED_BY(crit_);